The present invention relates to an antenna for the reception of meter waves in a motor vehicle, the antenna being arranged in a window pane provided with a metallic frame to form a substantially vertically unipole in the range of the vertical section plane of the pane.
As known, with antenna structures in motor vehicle panes it is possible to receive with a satisfactory efficiency all wave bands, for example long, medium and short wave bands as well as ultrashort broadcast wave bands. An advantage of this type of antenna is the fact that due to its integration into the vehicle body the requirements specific for motor vehicles, such as mechanical rigidity, longer service life, simpler assembly and the elimination of unnecessary air turbulation are much better than a standard rod antenna.
The invention is based on a known antenna described in the German Patent Application P 2,136,759 which is very suitable for the reception of frequencies of the ultrashort wavelengths. This prior art antenna employs a unipole in a metallic frame which may be constituted for example by the metal frame of a motor vehicle window pane, whereby the unipole in this specific application is applied on the glass pane within the frame. The antenna of this kind exhibits both for horizontal polarized waves as well as for the vertically or circularly polarized waves excellent reception quality and delivers an average signal level which is almost equivalent to that delivered by a telescopic antenna as is conventionally used in the motor vehicles.
However, in the antenna according to the application P 2,136,759 the crossing of the unipole with other conductive structures on the window pane, such as for example, with heating wire structures usually present in the window panes of modern motor vehicles is not permissible. Subsequently an antenna according to the application P 2,136,759 cannot be employed in motor vehicles in which a substantial portion of the window pane surface is covered by heating wires of the pane heating arrangement.